1pg2(3)                     Erlang Module Definition                     pg2(3)
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NAME

6       pg2 - Distributed named process groups.
7

DESCRIPTION

9       This module implements process groups. Each message can be sent to one,
10       some, or all group members.
11
12       A group of processes can be accessed by a common name. For example,  if
13       there  is  a group named foobar, there can be a set of processes (which
14       can be located on different nodes) that are all members  of  the  group
15       foobar.  There  are  no  special functions for sending a message to the
16       group. Instead, client functions are to be written with  the  functions
17       get_members/1  and get_local_members/1 to determine which processes are
18       members of the group. Then the message can be sent to one or more group
19       members.
20
21       If a member terminates, it is automatically removed from the group.
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23   Warning:
24       This  module  is  used by module disk_log for managing distributed disk
25       logs. The disk log names are used as group names, which means that some
26       action can be needed to avoid name clashes.
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28

DATA TYPES

30       name() = any()
31
32              The name of a process group.
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EXPORTS

35       create(Name :: name()) -> ok
36
37              Creates  a new, empty process group. The group is globally visi‐
38              ble on all nodes. If the group exists, nothing happens.
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40       delete(Name :: name()) -> ok
41
42              Deletes a process group.
43
44       get_closest_pid(Name) -> pid() | {error, Reason}
45
46              Types:
47
48                 Name = name()
49                 Reason = {no_process, Name} | {no_such_group, Name}
50
51              A useful dispatch function that can be used  from  client  func‐
52              tions. It returns a process on the local node, if such a process
53              exists. Otherwise, it selects one randomly.
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55       get_local_members(Name) ->
56                            [pid()] | {error, {no_such_group, Name}}
57
58              Types:
59
60                 Name = name()
61
62              Returns all processes running on the local  node  in  the  group
63              Name.  This function is to be used from within a client function
64              that accesses the group. It is therefore optimized for speed.
65
66       get_members(Name) -> [pid()] | {error, {no_such_group, Name}}
67
68              Types:
69
70                 Name = name()
71
72              Returns all processes in the group Name. This function is to  be
73              used  from  within a client function that accesses the group. It
74              is therefore optimized for speed.
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76       join(Name, Pid :: pid()) -> ok | {error, {no_such_group, Name}}
77
78              Types:
79
80                 Name = name()
81
82              Joins the process Pid to the group Name. A process  can  join  a
83              group  many  times and must then leave the group the same number
84              of times.
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86       leave(Name, Pid :: pid()) -> ok | {error, {no_such_group, Name}}
87
88              Types:
89
90                 Name = name()
91
92              Makes the process Pid leave the group Name. If  the  process  is
93              not a member of the group, ok is returned.
94
95       start() -> {ok, pid()} | {error, any()}
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97       start_link() -> {ok, pid()} | {error, any()}
98
99              Starts  the pg2 server. Normally, the server does not need to be
100              started explicitly, as  it  is  started  dynamically  if  it  is
101              needed.  This is useful during development, but in a target sys‐
102              tem the server is to be started explicitly. Use  the  configura‐
103              tion parameters for kernel(6) for this.
104
105       which_groups() -> [Name :: name()]
106
107              Returns a list of all known groups.
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SEE ALSO

110       kernel(6)
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114Ericsson AB                      kernel 6.5.2                           pg2(3)